Question

Isn’t ______ rude _______ him to talk to his mother like that?

1. A.
   that; for
2. B.
   he; of
3. C.
   it; for
4. D.
   it; of

Answer 1

D
本句中it为形式主语（值得注意的是只有it才能充当形式主语），真正的主语为不定式短语，不定式的逻辑主语常用介词for或of引出。形容词rude和him之间有内在联系，故用介词of。